LONDON (Reuters) - The whine of the dentist's drill can make
most people cringe, but researchers warn patients with weak
immune systems should also worry about potentially deadly
bacteria from oral water sprays used during treatment.
New Scientist magazine said Wednesday a British study showed
that people with conditions such as cancer or HIV were at risk
of getting more than just a gleaming smile.
James Walker and his team at the Center for Applied
Microbiology and Research found that levels of "opportunistic
pathogens" exceeded European Union limits in 52 of 55 water
samples taken at 21 dental surgeries in southwestern England.
The research was originally reported in the journal Applied and
"People with compromised immune systems should worry," David
Turner of the British Dental Association told New Scientist.
The bacteria found in the dental unit water lines (DUWs)
included species of Mycobacterium and Legionella which can both
cause life-threatening pneumonia.
Walker's team also isolated oral streptoccoci -- potentially
deadly bacteria which can cause scarlet fever and pneumonia --
in 10 percent of the samples.
"Since the bacteria is only found in the mouth, it is most
likely that during dental procedures it was sucked back into
the tools and into the DUW," New Scientist said.
Some of the highest bacterial counts were found in DUWs which
had been recently sanitized or supplied with bottled water,
casting doubt on recommendations for reducing risk put out by
the dental associations in Britain and the United States, it
"This is like sharing spit," Robert Staat, of the University of
Louisville's school of dentistry in the United States, said.
New Scientist said it was told by the American Dental
Association that similar studies in several U.S. cities had
revealed bacterial counts beyond safety guidelines.
Most of the bacteria in DUWs occur naturally and pose little
threat to people with healthy immune systems.
But Hugh Pennington, a microbiologist at the University of
Aberdeen in Scotland, said no one visiting the dentist should
be exposed to the levels discovered in Walker's study.